IPPM Working Group X. He Internet-Draft X. Chen Intended status: Standards Track China Telecom Expires: 7 January 2027 Z. He South China University of Technology 6 July 2026 IOAM Trace-Type Extensions for Path bandwidth draft-he-ippm-ioam-trace-type-bandwidth-00 Abstract Traffic scheduling and optimization have become routine network operation and maintenance tasks for operators. The operators need to select a path that can accommodate the capacity of the traffic to be scheduled. In situ Operations, Administration, and Maintenance (IOAM) is used for recording and collecting operational and telemetry information. This document defines two bit flags within IOAM Trace- Type for carrying bandwidth information. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 7 January 2027. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components He, et al. Expires 7 January 2027 [Page 1] Internet-Draft IOAM Trace-Type Extensions for Path band July 2026 extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Selecting A Path with Guaranteed Bandwidth . . . . . . . 4 3.2. DCI Traffic Scheduling among Multiple Backbone Networks . . . . . . . . . . . . . . . . . . . . . . . . 5 4. IOAM Trace-Type Extensions for Path bandwidth . . . . . . . . 6 4.1. IOAM Trace-Type Flags . . . . . . . . . . . . . . . . . . 6 4.2. IOAM Node Data Fields and Formats . . . . . . . . . . . . 6 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 7.1. Normative References . . . . . . . . . . . . . . . . . . 8 7.2. Informative References . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction Traffic scheduling and optimization have become routine network operation and maintenance tasks for operators. The operators need to select a path that can accommodate the capacity of the traffic to be scheduled. Typically, large network operators possess two nationwide backbone networks: one positioned as the public basic Internet backbone, featuring high capacity, high throughput, and best-effort service; the other positioned as a high-quality multi-service transport backbone network, with QoS guarantees and traffic engineering capabilities. For the former, the link utilization parameter provided by the network reflects the usage of network resources; while for the latter, the available bandwidth parameter provided by the network represents the capacity of new service traffic to be accepted. In situ Operations, Administration, and Maintenance (IOAM) [RFC9197] can collect operational and telemetry information in the packet while the packet traverses a path between two points in the network. Specifically, IOAM Trace Option can determine a path composed of a specific sequence of nodes and links that a packet flow traverses between an IOAM encapsulating node and an IOAM decapsulating node in a network. Therefore, IOAM may also be a practical tool capable of quickly discovering the available bandwidth of a path. He, et al. Expires 7 January 2027 [Page 2] Internet-Draft IOAM Trace-Type Extensions for Path band July 2026 RFC9486 defines IOAM Data-Fields encapsulated in IPv6. IOAM Direct Export (DEX) Option [RFC9326] is used as a trigger for IOAM data to be directly exported to a collector. [I-D.ietf-6man- icmpv6-reflection] specifies the ICMPv6 Reflection utility, which could be used for collecting IOAM data in the forward way as well as the reverse way, and this Reflection utility allows this information to be sent back to the probing node. Similarly, [I-D.ietf-ippm- stamp-ext-hdr] could be also used for collecting IOAM data in the forward way as well as the reverse way, in which the Simple Two-Way Active Measurement Protocol (STAMP) test packets are transmitted along a path between a Session-Sender and a Session-Reflector. This document defines two bit flags within IOAM Trace-Type for carrying bandwidth information. 2. Conventions 2.1. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 2.2. Terminology Abbreviations used in this document: AI: Artificial Intelligence AS: Autonomous System DEX: Direct Exporting DC: Data Center DCI: Data Center Interconnection ICMPv6: Internet Control Message Protocol version 6 IOAM: In situ Operation, Administration, and Maintenance MPLS: Multi-Protocol Label Switching QoS: Quality of Service P: Provider He, et al. Expires 7 January 2027 [Page 3] Internet-Draft IOAM Trace-Type Extensions for Path band July 2026 PE: Provider Edge PoP: Point of Presence SR-MPLS: Segment Routing over MPLS STAMP: Simple Two-Way Active Measurement Protocol 3. Use Cases 3.1. Selecting A Path with Guaranteed Bandwidth For many customers, ensuring service bandwidth is a basic requirement, so it is necessary to provide customers with bandwidth guaranteed delivery. Operators typically provide bearer services to such customers through SR-MPLS backbone networks with QoS guarantees and traffic engineering capabilities. In a single network domain scenario as depicted in Figure 1. +-------------------------------------------------+ | +--------+ | | /------->|P1...Pn |------->\ | | / +--------+ \ | | / \ | +---------+ | +----/------+ +-------+ +-----\----+ | +--------+ |Customer |--|-->|Ingress PE |---->|P1...Pn|---->|Egress PE |--|---->|Customer| |PoP | | +----\------+ +-------+ +-----/----+ | |PoP | +---------+ | \ / | +--------+ | \ +--------+ / | | \------->|P1...Pn |------->/ | | +--------+ | | SR-MPLS backbone network | +-------------------------------------------------+ Figure 1: Selecting A Path with Guaranteed Bandwidth The customer' Point of Presences (PoPs) are directly connected to the ingress PE and the egress PE of SR-MPLS backbone network, and there exist multiple paths from the ingress PE and the egress PE. In order to select an appropriate path that satisfies the bandwidth reqiurement, the ingress PE sends IOAM probe packets to the egress PE through different paths, and then the egress PE can reflect these IOAM probe packets to the ingress PE, carrying per-hop available bandwidth parameters. He, et al. Expires 7 January 2027 [Page 4] Internet-Draft IOAM Trace-Type Extensions for Path band July 2026 3.2. DCI Traffic Scheduling among Multiple Backbone Networks With the rapid growth in demand for computing and storage resources in AI big models and distributed storage, cloud computing centers are interconnected through backbone networks to provide multi-DCs collaboration to compensate for the limitations of insufficient computing and storage resources in a single DC, and improve resource utilization. In multiple network domain scenario as depicted in Figure2, the cloud Data Center (DC) Gateways are connected to multiple backbone networks to schedule traffic for load balancing. +---------------------------------------------------+ | +----------+ +--------+ +----------+ | +---------|---|Ingress PE|-----|P1...Pn |------|Egress PE |---|--------+ | | +----------+ +--------+ +----------+ | | | | IP Internet backbone network | | | +---------------------------------------------------+ | | +---------------------------------------------------+ | +----+-----+ | +----------+ +--------+ +-----------+ | +----+-----+ | Cloud DC |---|---|Ingress PE|-----|P1...Pn |------|Egress PE |--|---| Cloud DC | | Gateway | | +----------+ +--------+ +-----------+ | | Gateway | +----+-----+ | Cloud backbone network | +----+-----+ | +---------------------------------------------------+ | | +---------------------------------------------------+ | | | +----------+ +--------+ +----------+ | | +---------|---|Ingress PE|-----|P1...Pn |------|Egress PE |---|--------+ | +----------+ +--------+ +----------+ | | SR-MPLS backbone network | +---------------------------------------------------+ Figure 2: DCI Traffic Scheduling among Multiple Backbone Networks Since these networks belong to different administrative domain with differnet AS number, it is difficult for the cloud DCs obtain the availabe bandwidth information of path from backbone networks, the source DC Gateway of cloud Data Center is required to send IOAM probe packets to the destination DC Gateway of cloud Data Center through multiple backbone networks, and then the destination DC Gateway can reflect these IOAM probe packets to the source DC Gateway, carrying per-hop available bandwidth parameters. Consequently, the source DC Gateway steers partial traffic into other backbone networks to mitigate the cloud backbone network. For IP Internet backbone as mentioned above, which can only provide best-effort service, the available bandwidth parameter cannot be calculated or configured by network node, thus it is not available, He, et al. Expires 7 January 2027 [Page 5] Internet-Draft IOAM Trace-Type Extensions for Path band July 2026 collecting per-hop link utilization parameters is preferable. In addition, multiple interface rates coexist on IP Internet backbone, including 100 Gb/s, 200 Gb/s, 400 Gb/s, etc. per-hop link bandwidth (i.e., interface rate) parameters are also required to be collected. Typically, the peak link utilization should not exceed 90%. Based on per-hop link utilization together with per-hop link bandwidth along the path, we can roughly calculate the amount of traffic to be added to the path. For example, an IOAM probe packet traverses a path with 3 nodes within IP Internet backbone: the first node has a link utilization of 50% together with a link bandwidth of 100 Gb/s, the second node has a link utilization of 60% together with a link bandwidth of 200 Gb/s, and the third node has a link utilization of 70% together with a link bandwidth of 400 Gb/s. We can calculate that the first node has the available bandwidth of 40 Gb/s, the second node has the available bandwidth of 60 Gb/s, and the third node has the available bandwidth of 80 Gb/s, thus we can determine that this path could still accommodate up to 40Gb/s of traffic. 4. IOAM Trace-Type Extensions for Path bandwidth 4.1. IOAM Trace-Type Flags IOAM Trace-Type defined in [RFC9197] is a 24-bit identifier that specifies which data types are used in the node data list. The IOAM Trace-Type value is a bit field. This document defines two bit flags within IOAM Trace-Type for carrying bandwidth information as follows: Bit 12: When set, indicates the presence of link utilization and link bandwidth in the node data. Bit 13: When set, indicates the presence of available bandwidth in the node data. 4.2. IOAM Node Data Fields and Formats All the IOAM-Data-Fields MUST be aligned by 4 octets. If a node that is supposed to update an IOAM-Data-Field is not capable of populating the value of a field set in the IOAM Trace-Type, the field value MUST be set to 0xFFFFFFFF for 4-octet fields, indicating that the value is not populated. The link utilization and link bandwidth field is a 4-octet field that is defined as follows: He, et al. Expires 7 January 2027 [Page 6] Internet-Draft IOAM Trace-Type Extensions for Path band July 2026 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | link utilization | Rsvd | link bandwidth | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Link utilization: 2-octet unsigned integer field as a percentage of the link utilization, restricted to [0x0000,0xffff], with value 0x0000 indicating a link utilization of 0%, and value 0xffff indicating a link utilization of 100%. The resolution is 0.0015%. Link bandwidth: 2-octet unsigned integer field. The lower 11 bits of this field are defined as the standardized interface rates. The higher 5 bits of this field are reversed for future use, and they MUST be all zero on transmission and ignored on receipt. The link bandwidth is defined as follows: * Bit 0: When set, indicates the link bandwidth of 10Mb/s. * Bit 1: When set, indicates the link bandwidth of 100Mb/s. * Bit 2: When set, indicates the link bandwidth of 1Gb/s. * Bit 3: When set, indicates the link bandwidth of 10Gb/s. * Bit 4: When set, indicates the link bandwidth of 50Gb/s. * Bit 5: When set, indicates the link bandwidth of 100Gb/s. * Bit 6: When set, indicates the link bandwidth of 200Gb/s. * Bit 7: When set, indicates the link bandwidth of 400Gb/s. * Bit 8: When set, indicates the link bandwidth of 800Gb/s. * Bit 9: When set, indicates the link bandwidth of 1.6Tb/s. * Bit 10: When set, indicates the link bandwidth of 3.2Tb/s. The available bandwidth field is a 4-octet field that is defined as follows: 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | available bandwidth | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ He, et al. Expires 7 January 2027 [Page 7] Internet-Draft IOAM Trace-Type Extensions for Path band July 2026 Available bandwidth: 4-octet unsigned integer field, defined in [RFC8570]. This field carries the available bandwidth on a link in IEEE floating-point format with units of bytes per second. 5. IANA Considerations IANA has defined an "IOAM Trace-Type" Registry. This registry defines code points for each bit in the 24-bit IOAM Trace-Type field for the Pre-allocated Trace Option-Type and Incremental Trace Option- Type defined in [RFC9197]. Bit 0-11 are defined in RFC9197. Bit 12 and Bit 13 are defined in this document. IANA is requested to allocate the following code point from the "IOAM Trace-Type" registry: Bit 12: TBA. Description: link utilization and link bandwidth. Reference: This document. Bit 13: TBA. Description: available bandwidth. Reference: This document. 6. Security Considerations The security considerations of IOAM in general are discussed in [RFC9197], the security considerations of IOAM DEX Option-Type are discussed in [RFC9326]. The security considerations for using the ICMPv6 Reflection utility are discussed in [I-D.ietf-6man- icmpv6-reflection], and the security considerations for using STAMP are discussed in [I-D.ietf-ippm-stamp-ext-hdr] . There are not additional security considerations in this Extended IOAM Trace-Type. 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . He, et al. Expires 7 January 2027 [Page 8] Internet-Draft IOAM Trace-Type Extensions for Path band July 2026 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC9197] Brockners, F., Ed., Bhandari, S., Ed., and T. Mizrahi, Ed., "Data Fields for In Situ Operations, Administration, and Maintenance (IOAM)", RFC 9197, DOI 10.17487/RFC9197, May 2022, . [RFC9326] Song, H., Gafni, B., Brockners, F., Bhandari, S., and T. Mizrahi, "In Situ Operations, Administration, and Maintenance (IOAM) Direct Exporting", RFC 9326, DOI 10.17487/RFC9326, November 2022, . 7.2. Informative References [I-D.ietf-6man-icmpv6-reflection] Mizrahi, T., hexiaoming, X., Zhou, T., Bonica, R., and X. Min, "Internet Control Message Protocol (ICMPv6) Reflection", Work in Progress, Internet-Draft, draft-ietf- 6man-icmpv6-reflection-19, 15 December 2025, . [I-D.ietf-ippm-stamp-ext-hdr] Gandhi, R., Zhou, T., Li, Z., and W. Hawkins, "Simple Two- Way Active Measurement Protocol (STAMP) Extensions for Reflecting STAMP Packet IP Headers", Work in Progress, Internet-Draft, draft-ietf-ippm-stamp-ext-hdr-11, 4 July 2026, . [RFC8570] Ginsberg, L., Ed., Previdi, S., Ed., Giacalone, S., Ward, D., Drake, J., and Q. Wu, "IS-IS Traffic Engineering (TE) Metric Extensions", RFC 8570, DOI 10.17487/RFC8570, March 2019, . [RFC9486] Bhandari, S., Ed. and F. Brockners, Ed., "IPv6 Options for In Situ Operations, Administration, and Maintenance (IOAM)", RFC 9486, DOI 10.17487/RFC9486, September 2023, . Authors' Addresses Xiaoming He China Telecom Email: hexm4@chinatelecom.cn He, et al. Expires 7 January 2027 [Page 9] Internet-Draft IOAM Trace-Type Extensions for Path band July 2026 Xun Chen China Telecom Email: chenxun@chinatelecom.cn Zijing He South China University of Technology Email: katehe163@163.com He, et al. Expires 7 January 2027 [Page 10]